1. Technical Field
The invention relates to the field of display technology, and more particularly to a method for manufacturing a TFT substrate and a TFT substrate manufactured thereof.
2. Description of the Related Art
With the enhancement of tablet display technology, requirements of panels with high resolution and low energy consumption are rising. Due to electronic mobility is high, much attention has been devoted to low temperature poly-silicon (LTPS) in realms of liquid crystal display (LCD) and organic light emitting diode (OLED), LTPS is regarded as a critical material for realizing a full-color tablet display with a small budget. To tablets, a low temperature poly-silicon material takes advantage of high resolution, rapid response time, highlight, high aperture opening ratio, low energy consumption, and a low temperature poly-silicon can be manufactured at low temperatures, and regarded as a subject of extensive study for using in producing a complementary metal oxide semiconductor (C-MOS) circuit to meet the requirements of high resolution and low energy consumption of panels.
At the beginning period of development of poly-silicon technology, a high temperature oxidation process of laser anneal is applied to convert a glass substrate from amorphous silicon to poly-silicon in order to produce high temperature poly-silicon (HTPS), the temperature of the glass substrate will be more than 1000° at this point. Compared with conventional high temperature poly-silicon, low temperature poly-silicon needs laser irradiation as well, but an excimer laser is used as a heat source, after passing through a transmission system, a laser forms a laser beam that energy distributes evenly and projected on to an amorphous silicon glass substrate, after absorbing energy of the excimer laser, an amorphous silicon glass substrate will converts into a glass substrate with poly-silicon structure. As the entire process is basically done below 600° C., a temperature most glass substrates can endure, costs of manufacture can be reduced. Besides costs reduction of manufacture, other advantages of low temperature poly-silicon include faster electronic mobility and better stability.
Methods for manufacturing low temperature poly-silicon include solid phase crystallization (SPC), metal-induced crystallization (MIC) and excimer laser annealing (ELA). Among which, ELA is the most widely spread and sophisticated way to manufacture low temperature poly-silicon, the process mainly is: forming a buffering layer on the glass substrate, then forming an amorphous silicon layer on the buffering layer, dehydrogenating by high temperature, utilizing an ELA laser beam to scan the amorphous silicon so as to execute excimer laser annealing, the amorphous silicon absorbing energy from the laser and reaching high temperature in a very short time and then melting, finally cooling to recrystallize into poly-silicon. The fact encountered currently is that low temperature poly-silicon thin film transistors produced by the method ELA are not identity and over budget, the method SPC can decrease costs and increase identity, but open current and slope of subthreshold are defeated by low temperature poly-silicon thin film transistors produced by ELA, and off-current is big, because of which the drive capacity is poor.